1. Field of the Invention
The invention relates to a network arrangement for wirelessly locating or determining the position of objects within a confined space and a method for operating it, according to the preamble of the respective independent claims. The subject matter of the present invention is also a computer program and a machine-readable data storage device for storing the computer program, by means of which the method according to the invention is able to be carried out.
2. Description of the Related Art
In the field of industrial factory halls, production halls, factory premises or similar, it is known to spatially locate moving objects by means of wireless or radio localization. Such objects are automatic pallet trucks or devices (“Automated Guided Vehicles—AGV”), which are used in automated guided vehicle systems. These trucks are guided automatically and move along a real or virtual line marking without human operation. In the fields of warehousing or industrial production, it can involve locating steel products such as slabs or coils that haven been deposited in a steelwork, for example, wherein the objects, however, can also be autarkic robot vehicles, forklift trucks or similar. Thus, a one-dimensional location can take place along a lane guidance, for example, of a crane, a two-dimensional location on a flat surface or a spatial location of objects, for example in a three-dimensional storage system.
Such a radio locating system is known from U.S. Pat. No. 6,133,876 which is comprehensively referenced by means of the “Incorporation by Reference”, and relates to a method and a network arrangement for determining position by means of pulse-shaped radio signals (so-called “impulse radio system”). Thus, a first transceiver having a first cycle and a second transceiver, which is distanced from the first transceiver and has a second cycle, are provided. Using the first cycle, a first reference cycle impulse is produced and a first series of impulses is broadcast by the first transceiver by this reference cycle impulse. This first series of impulses is received by the second transceiver and the second transceiver is synchronized by means of these impulses. Using the second cycle, a second reference cycle impulse is produced by the second transceiver and with this a second series of impulses is broadcast by the second transceiver. The first transceiver receives this second series of impulses and carries out a synchronization with it. On the basis of this synchronization, a first reference cycle impulse that is correspondingly delayed in time is produced and out of this, the time difference between the first reference impulse and the delayed first reference impulse is determined, wherein this time difference indicates the total running time of the first and the Second series of impulses.
A locating system based on ultra-wideband (UWB) signals and correspondingly on running time or flight time measurements emerges from U.S. Pat. No. 7,873,099, in which a UWB receiver of a corresponding data communication net synchronizes receiver-side time information, based on a received signal structure, wherein the time information is demodulated and wherein the demodulated time information is used to set a receiver-side cycle. The receiver-side cycle is adjusted by means of information about the running time delay, and namely by increasing the cycle value in order to compensate said running time delay. The running time delay is determined on the basis of a previously known distance between the sender and the receiver, wherein the sender and the receiver can be part of a two-way connection and wherein the running time delay is determined by measuring a package circulation period (so-called “round trip timing”), i.e. by measuring the time that a data package in the data communication net requires to broadcast from the sender to the receiver and back.